diff --git a/serialutils.py b/serialutils.py
index d6f963c..f4e0458 100644
--- a/serialutils.py
+++ b/serialutils.py
@@ -9,6 +9,9 @@ def find_cam_port():
     return None
 
 def send_serial_cmd(cam_port, cmd:str, clear=True):
+    if cam_port is None:
+        print("No com. port found.")
+        return False
     con = serial.Serial(cam_port, baudrate=115200)
     if clear:
         append = b'\rclear\r'